Long-Term Evolution (LTE) is a standard for high-speed wireless communication for mobile devices. With the development of mobile communication technologies, Voice over LTE (VoLTE) is gradually mature. As VoLTE technology is a type of Internet Protocol (IP) data transmission technology, the terminal can realize the voice service based on Internet Protocol Multimedia Subsystem (IMS) through the VoLTE technology. That is, a user terminal can make a voice call with a terminal of a contact via VoLTE technology.
In the related arts, when the user terminal makes a voice call with the terminal of a contact via VoLTE technology, the user terminal needs to select corresponding coding format and code rate for voice encoding by negotiation with a core network equipment according to current network connection condition, and then makes the voice call with the terminal of a contact with the selected coding format and code rate.